1972’s “Deep Throat” was the porn flick that took blowjobs out of the closet and put them on “The Tonight Show.” It’s star was by far the most famous pornographic performer of all time and, it turns out, a victim of shocking abuse.

The only surviving film of a pair of planned projects about the woman who will forever be known as Linda Lovelace, “Lovelace” stars Amanda Seyfried as Linda and Peter Sarsgaard as her first husband, sexual Svengali and tormentor, Chuck Traynor. The most interesting thing about “Lovelace” is its structure. The film breaks down pretty clearly into two parts: one largely comedic, the other brutally tragic.

Part one is mostly a shockingly cheerful porn biopic that will please those who are longing for a less weighty “Boogie Nights” follow-up. It shows us how a sleazy but nevertheless charming and love struck Traynor seduces sweet and only slightly damaged 21-year-old Linda Boreman away from her unpleasantly rigid, super-traditional Catholic mom (Sharon Stone), her low-key security officer dad (Robert Patrick) and her understandably suspicious best friend (Juno Temple). The tone grows more blackly comedic as skeezy Chuck gets involved with pornsters and sells them on his wife’s borderline disturbing ability to suppress her gag reflex. Linda Lovelace is born.

Sometime after we see Hugh Hefner (a miscast James Franco) suggest that life should imitate art in a very specific way during a screening of the now hugely successful “Deep Throat,” “Lovelace” abruptly takes us six years later into 1980 as Linda Marchiano – she’s now married to apparent good-guy cable installer Chuck Marchiano (Wes Bentley) – passes a polygraph test and promotes her book, “Ordeal,” on the “Phil Donahue Show.” Just as abruptly, the film circles back to give us Linda’s very personal point of view of the events surrounding “Deep Throat.” It’s no prettier than the visible bruises on her legs.

Traynor, it turns out, is not so much the manipulative but charming sleazebag he was in the first half of the film, but a monstrous nightmare husband – a torturer and serial rapist; the kind of guy who would literally sell his alleged true love to the highest bidder or, in one horrific instance, several bidders. Worse, he’s found the perfect victim. When Linda runs home after being prostituted and abused by Chuck, her mother’s reaction is to sell her own daughter down the river. Better a husband who is also a rapist/torturer than the shame of a broken marriage.

“Lovelace” takes a far more traditional cinematic approach than “Howl,” the earlier fact-based fiction film from documentarians Rob Epstein and Jeffrey Friedman; it was more like a dramatized documentary than a movie in the ordinary sense, while “Lovelace” won’t seem out of place on most cable TV outlets. At the same time, however, the two-part structure is a biting comment on the inherently selective nature of media. Film might be truth 24 times a second, Jean-Luc Godard told us, but he also said that every cut is a lie.

That’s fine, but I wish there was more to it. There’s a fascinating political dimension to the Linda Lovelace story that “Lovelace” takes great pains to avoid. Linda Marchiano made a religious argument against pornography while also falling in with mainstream feminist heroine Gloria Steinem and two hugely divisive intellectual flamethrowers from the most radical wing of feminism, Andrea Dworkin and Catherine Mackinnon, who at times made common cause with the religious right in their efforts to destroy the porn industry. To Dworkin and Mackinnon, the porn industry included such non-hardcore venues as Playboy magazine and far milder material as well. Even so, I wouldn’t mind seeing an honest and open look at the arguments around pornography, particularly hardcore. It’s big business and a huge part of modern life. Let’s talk about it.

Still, as a mostly apolitical black comedy and dark melodrama, “Lovelace” works reasonably well, and that’s mostly due to a strong pace and a stronger cast. I’ve been intrigued by Amanda Seyfried since catching her a few years back in Atom Egoyan’s underrated “Chloe,” where she also played a sex worker well out of her depth. Her performance as Linda Lovelace is a solid blend of vulnerability, strength and deep emotional pain, though I think she might be capable of even more. Co-star Peter Saarsgard is another favorite, and he’s just fine here, adding some real physical menace to a role that could otherwise be seen as a call back to his performance as a less violent corrupter of young women in 2009’s “An Education.”

In a sizable role, Sharon Stone is memorable – and memorably unpleasant – as Linda’s anger-driven mother, and as Linda’s father, Robert Patrick is devastating in a scene where he tells Linda he saw “her movie.” As for the actors in less central roles, Hank Azaria is, predictably enough, very funny as horribly be-toupeed porn auteur Gerald Damiano, and Chris Noth is chilling, but also strangely sympathetic and as interesting as I’ve ever seen him, as a mobster a bit taken aback by the unpleasantness inside the Lovelace/Traynor marriage.

Still, most interesting of all the supporting roles is Adam Brody’s Harry Reems. Brody makes Reems a truly sympathetic presence, bringing out plenty of humor while also hinting that, on some level, Reems might be almost as much as victim as Linda. In real life, Reems was jailed on obscenity charges and fought a lengthy legal battle with the help of none other than Alan Dershowitz while also fighting a persistent battle with hard drugs. I wouldn’t mind seeing that movie, either.